variations in the intensity and quantity of the electric fluid.

372. In order to procure a reference to _chemical action_, the wires were
now retained immersed in the acid to the depth of five eighths of an inch,
and the needle, when stationary, observed; it stood, as nearly as the
unassisted eye could decide, at 5-1/3 division. Hence a permanent
deflection to that extent might be considered as indicating a constant
voltaic current, which in eight beats of my watch (369.) could supply as
much electricity as the electrical battery charged by thirty turns of the
machine.

373. The following arrangements and results are selected from many that
were made and obtained relative to chemical action. A platina wire one
twelfth of an inch in diameter, weighing two hundred and sixty grains, had
the extremity rendered plain, so as to offer a definite surface equal to a
circle of the same diameter as the wire; it was then connected in turn with
the conductor of the machine, or with the voltaic apparatus (369.), so as
always to form the positive pole, and at the same time retain a
perpendicular position, that it might rest, with its whole weight, upon the
test paper to be employed. The test paper itself was supported upon a
platina spatula, connected either with the discharging train (292.), or
with the negative wire of the voltaic apparatus, and it consisted of four
thicknesses, moistened at all times to an equal degree in a standard
solution of hydriodate of potassa (316.).

374. When the platina wire was connected with the prime conductor of the
machine, and the spatula with the discharging train, ten turns of the
machine had such decomposing power as to produce a pale round spot of
iodine of the diameter of the wire; twenty turns made a much darker mark,
and thirty turns made a dark brown spot penetrating to the second thickness